The invention lies in the field of locking means for pins applied to join and permit rotation of two elements with respect to each other.
More particularly, it concerns the method of locking a pin within a series of openings between at least two members, so that the members can rotate with respect to each other, while the pin is prevented from moving longitudinally out of the openings.
In the prior art, in the construction of machinery, it is often necessary to connect two machine elements or arms, by using a pin about which they can rotate. There have been devised many methods of securing the pin from drifting from containment within each of the elements. Such restraining devices that have been used are, for example, cotter pins, nuts, roll pins, spring pins, safety wire, ball detent plungers, locking rings, snap rings, etc. All of these devices either project beyond the outer surfaces of the machine members in their most simple form, or require the machine member to be complex in shape to guard the pin securing device. This adds additional cost and requires special tools for the assembly and disassembly of the machine elements.
Many of the above devices are applicable only in non-load bearing situations. Further, a roll pin which is driven through the two connecting machine elements by the use of a hammer and grabs one of the machine elements by the expansive outer force caused by the compression of the roll pin, has a weakness in that the pin is hollow in shape and split longitudinally. For this reason, it has less bending strength than a solid pin of equal outer diameter.
A grooved pin is slotted during manufacturing so as to develop sharp projections along the edges of the slot and is then heat treated into a hardened condition, and can be driven into the machine elements by the use of a common hammer. The sharp projections cut into one of the machine elements thereby securing the pin in position. However, when the pins are removed and reapplied several times, in the same machine element, the cutting effect of the sharp projections enlarged the internal diameter of the machine element opening, and make the later holding of the pin impossible.